There are a large number of hardness testing methods available (e.g. Vickers, Brinell, Rockwell, Meyer and Leeb). Although it is impossible in many cases to give an exact conversion, it is possible to give an approximate material-specific comparison table e.g. for steels.

Hardness comparison table[edit]

Brinell HB (10 mm Ball, 3000 kg load)	Vickers HV (1 kg)	Rockwell C HRC (120 degree cone 150 kg)	Rockwell B HRB (1/16' ball 100 kg)	Leeb HLD[1]
800	-	72	-	856
780	1220	71	-	850
760	1210	70	-	843
745	1114	68	-	837
725	1060	67	-	829
712	1021	66	-	824
682	940	65	-	812
668	905	64	-	806
652	867	63	-	799
626	803	62	-	787
614	775	61	-	782
601	746	60	-	776
590	727	59	-	770
576	694	57	-	763
552	649	56	-	751
545	639	55	-	748
529	606	54	-	739
514	587	53	120	731
502	565	52	119	724
495	551	51	119	719
477	534	49	118	709
461	502	48	117	699
451	489	47	117	693
444	474	46	116	688
427	460	45	115	677
415	435	44	115	669
401	423	43	114	660
388	401	42	114	650
375	390	41	113	640
370	385	40	112	635
362	380	39	111	630
351	361	38	111	622
346	352	37	110	617
341	344	37	110	613
331	335	36	109	605
323	320	35	109	599
311	312	34	108	588
301	305	33	107	579
293	291	32	106	572
285	285	31	105	565
276	278	30	105	557
269	272	29	104	550
261	261	28	103	542
258	258	27	102	539
249	250	25	101	530
245	246	24	100	526
240	240	23	99	521
237	235	23	99	518
229	226	22	98	510
224	221	21	97	505
217	217	20	96	497
211	213	19	95	491
206	209	18	94	485
203	201	17	94	482
200	199	16	93	478
196	197	15	92	474
191	190	14	92	468
187	186	13	91	463
185	184	12	91	461
183	183	11	90	459
180	177	10	89	455
175	174	9	88	449
170	171	7	87	443
167	168	6	87	439
165	165	5	86	437
163	162	4	85	434
160	159	3	84	430
156	154	2	83	425
154	152	1	82	423
152	150	-	82	420
150	149	-	81	417
147	147	-	80	413
145	146	-	79	411
143	144	-	79	408
141	142	-	78	405
140	141	-	77	404
135	135	-	75	397
130	130	-	72	390
114	120	-	67	365
105	110	-	62	350
95	100	-	56	331
90	95	-	52	321
81	85	-	41	300
76	80	-	37	287

Re: Rockwell, Brinell, Vickers Conversion - Evalauting aluminum 6061-T6 and 6063-T6 For the 'official' information, get a copy of ASTM E140, Standard Hardness Conversion Table for Metals, Relationship Among Brinell Hardness, Vickers Hardness, Rockwell Hardness, Superficial Hardness, Knoop Hardness and Scleroscope Hardness.

References[edit]

1. ^H.Pollok, „Umwertung der Skalen“ (“Conversion of Scales”), Qualität und Zuverlässigkeit, Ausgabe 4/2008.

External links[edit]

• Rockwell to Brinell conversion chart (Brinell, Rockwell A,B,C)
• Struers hardness conversion table (Vickers, Brinell, Rockwell B,C,D)

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Rockwell Hardness

Brinell Hardness

Vickers Hardness

Definition of Hardness

Hardness is a measure of how well a solid material resists permanent shape change when a compressive force is applied. Hardness is dependant on many factors including strength of intermolecular bonds, ductility, elastic stiffness, plasticity, strain, strength, toughness, and many more.

Hardness Tests: Measuring Hardness

There are three ways hardness is typicall measured:

Scratch Hardness

Scratch Hardness testing is based on the idea that harder materials will scratch softer materials.

Indentation Hardness

A typical hardness tester…

Indentation hardness measures the resistance of a sample to deformation due to a constant compression load from a sharp object. After the material under test is subjected to a specially loaded and dimensioned indenter, the dimensions of the indentation left behind in the test subject determine the hardness.

This is the most common method of hardness testing used for CNC and machining purposes, and the Rockwell, Vickers, Shore, and Brinell Hardness scales are all based on Indentation Hardness.

Rebound Hardness

In Rebound Hardness measurements, the height of the “bounce” of a dimaond tipped hammer dropped from a fixed height onto the test material determines its hardness.

Rockwell Hardness Test (HR)

In the Rockwell Hardness Test (whose values are referred to with the abbreviation “HR”), a diamond cone or steel ball indenter is used. The indenter is forced into the test material under a minor load, usually 10 kgf. When equilibrium is reached (i.e. no further indentation at that load is happening), a datum position is established. An additional major load is applied, which increases penetration. Removing the major load results in a minor recovery of the material in most cases. The difference between the indentation after that minor recovery and the datum established by the minor load may be used to calculate the Rockwell hardness number.

The various Rockwell Hardness Scales differ in the nature of the indenter as well as the Major Load:

Testing parameters for the various Rockwell Hardness Scales…

The Rockwell Hardness Test is conveient to automate, but it suffers from many arbitrary scales and possible effects from the specimen support anvil. The Vickers and Brinell methods don’t suffer from this effect.

Brinell Hardness Test (BHN)

The Brinell Hardness Test consists of indenting the test material with a 10mm diameter hardened steel or carbide ball subjected to a load of 3000 kg. For softer materials, there are alternate scales using a 1500 kg or 500 kg load to avoid excessive indentation.

The full load is applied for 10 to 15 seconds for iron or steel and at least 30 seconds for other materials. The diameter of the indentation left is measured by a low powered microscope. The Brinell Hardness Number may be calculated from the diameter of that indentation. The average of two measurements taken at right angles is used for the diameter to ensure accuracy.

Compared to the other test methods, the Brinell ball makes the deepest and widest indentation, so the test results average hardness over a wider area. This can result in more accurate results when there are multiple grain structures and other irregularities in material uniformity.

Vickers Hardness Test (HV)

The Vickers Hardness Test uses a diamond indenter in the form of a right pyramid with a square base and an angle of 136 degress between opposite faces. The indenter is subjected to a load of 1 to 100 kgf. the full load is applied for 10 to 15 seconds. The two diagonals left in the surface of the material are measured using a microscope and their average is taken. From this, the area of the sloping surface of the indentation is calculated, and from that the Vickers Hardness may be determined.

Surprisingly, different loading settings give practically identical hardness numbers on uniform material, which is much better than the arbitrary changing of scale with the other hardness testing methods. The advantages of the Vickers hardness test are that extremely accurate readings can be taken, and just one type of indenter is used for all types of metals and surface treatments. The disadvantage is that the machines that take the reading are large floor-standing units (not benchtop), and they’re more expensive than Brinell or Rockwell machines.